The smoke produced by burning tobacco products is known as second-hand tobacco smoke or environmental tobacco smoke. Tobacco smoke in enclosed spaces is breathed by everyone, exposing both smokers and non-smokers to its harmful effects. This is commonly referred to as involuntary smoking or passive smoking. There are about 4000 known chemicals in tobacco smoke.

Second-hand smoke also causes heart disease and many serious respiratory and cardiovascular diseases in adults which can lead to death.

It causes cancer, heart disease and many other serious diseases in adults. Almost half of the world's children breathe air polluted by tobacco smoke, which worsens their asthma conditions and causes dangerous diseases. At least 200,000 workers die every year due to exposure to second-hand smoke at work.

Tobacco is the leading preventable cause of death in the world. It causes 1 in 10 deaths among adults worldwide. In 2005, tobacco caused 5.4 million deaths, or an average of one death every 6 seconds. At the current rate, the death toll is projected to reach more than 8 million annually by 2030 and a total of up to one billion deaths in the 21st century.

Ensuring a smoke-free environment is the only way to protect ourselves from the lethal ill effects of tobacco smoke.

The International Labour Organization estimates that at least 200,000 workers die every year due to exposure to smoke at work. The United States Environmental Protection Agency estimates that second-hand smoke is responsible for about 3,000 lung cancer deaths annually among non-smokers in the country. Exposure to second-hand smoke also imposes economic costs on individuals, businesses and society as a whole, in the form of direct and indirect medical costs and productivity losses.

There is no safe level of exposure to second-hand tobacco smoke. Neither ventilation nor filtration, even in combination, can reduce the exposure indoors to levels that are considered acceptable. Only 100% smoke-free environments provide effective protection.